1. Technical Field
The present disclosure relates to methods of making implantable medical devices having a coating that produces a specific chemotactic response.
2. Background of Related Art
Techniques for repairing damaged or diseased tissue are widespread in medicine. Wound closure devices such as sutures, staples and other repair devices such as mesh or patch reinforcements are frequently used for repair. Surgical adhesives have been used to augment and, in some cases, replace sutures and staples in wound closure. For example, in the case of hernias, techniques involving the use of a mesh or patch to reinforce the abdominal wall are being used. The mesh or patch can generally be held in place by suturing or stapling to the surrounding tissue. Unfortunately, the use of such sutures or staples may increase the patient's discomfort and, in certain instances, there may be a risk of weakening thin or delicate tissue where they are attached. Certain techniques involve placing a mesh or patch against the repair site without suturing or stapling, e.g., allowing the pressure of the peritoneum to hold the patch against the posterior side of the abdominal wall. However, fixation of the mesh or patch is generally preferred in order to avoid folding, shrinkage, and migration of the mesh or patch. Surgical adhesives such as cyanoacrylates and fibrin glues have been used as fixatives in lieu of, or in addition to, suturing or stapling the mesh or patch. However, fibrin adhesives can be difficult to prepare and store. Cyanoacrylates may cause irritation at the point of application and may not provide a sufficient degree of elasticity. In addition, surgical adhesives can tend to form a physical barrier between the item or items being attached to biological tissue, thus interfering with tissue ingrowth into the item when ingrowth is desired.
Click chemistry is a popular term for reliable reactions that make it possible for certain chemical building blocks to “click” together and form an irreversible linkage. Since its recent introduction, click chemistry has been used for ligation in biological and medical technology. In the case of azide-alkyne click chemistry, the reactions may be catalyzed or uncatalyzed, as illustrated in US Patent Publication. No. 2005/0222427 and PCT P2006/050262, respectively. Copper-free click chemistry was recently developed by Bertozzi and colleagues using difluorinated cyclooctyne or DIM, that reacts with azides rapidly at physiological temperatures without the need for a toxic catalyst as disclosed in Baskin et al., “Copper Free Click Chemistry for Dynamic In Vivo Imaging,” PNAS, vol. 104, no. 43, 16793-16797 (Oct. 23, 2007). The critical reagent, a substituted cyclooctyne, possesses ring strain and electron-withdrawing fluorine substituents that together promote a [3+2] dipolar cycloaddition with azides as disclosed in US Patent Publication No. 2006/0110782 and “Codelli et al., Second Generation Difluorinated Cyclooctynes for Copper-Free Click Chemistry,” J. Am. Chem. Soc., vol. 130, no. 34, 11486-11493 (2008). Another suitable cyclooctyne is 6,7-dimethoxyazacyclooct-4-yne (DIMAC) as disclosed in Sletton and Bertozzi, “A Hydrophilic Azacyclooctyne for Cu-free Click Chemistry,” Org. Lett. (2008) 10 (14), 3097-3099. Other click chemistry reactions include Diels-Alder reactions, thiol-alkene reactions, and maleimide-thiol reactions.
Implantable medical devices are formed from a variety of different biodegradable and non-biodegradable materials. Non-biodegradable devices offer increased strength and support, however, some medical devices do not fully integrate within the tissue due poor cell seeding within the devices. Accordingly, it would be beneficial to provide a medical device which includes a coating that encourages cell attachment thereto.